Unfortunately it’s not possible to change a domain name once the domain has been successfully registered for you. This is because domain names are bespoke (made for you) product and the registration fee is paid in advance to the registry to secure your domain for you.
If you no longer require your domain you can disable auto renew and it will expire at the end of the current registration term.
If you want a different domain name you’ll need to register a new domain in the same way your existing domain was registered.
